Automatic telephone system



A. J RAY ET AL AUTOMATIC TELEPHONE SYSTEM Filed Sept. 20. 1920 i Hfihur' JEE H FYJFFTF UZZ Patented Oct. 9, 1923. I

UNITED STATES I 1,469,809 PATENT orr ca.

ARTHUR J. BAY, OF CHICAGO, AND HERBERT F. OBEFGFELL, OF AUSTIN,v ILLINOIS, A8.

SIGNORS TO AUTOMATIC ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A. CORPORA- TION OI ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Application filed September 20, 1820. Serial No. 411,568.-

To all whom it may concern Be it known that we, ARTHUR J. RA! and HERBERT l ()BERGFELL, both citizens of the United States of America, and residents of Chicago, Cook County, Illinois, and Austin, ("ook County, Illinois, respectively have invented certain new and useful lmprovements in Automatic Telephone Systems, of which the following is a specification.

()ur invention relates in general to automatic telephone systems in which connecllOllS are estab'ished through the medium of subscriber controlled automatic switches, but is more particularly concerned with such automatic systems as include party lines and selective ringing ctpiipment at the exchange; and the object o the invention may be stated in general terms to be the provision of a new and improved automatic party line selective ringin system.

A number 0 different methods of selectively signalling the stations on the party lines have been practiced before. this. One method which has been used to some extent involves a provision of a small auxi'iary switch for each party line connector. Any station on a party line may' be called from any one of the connectors which have access to that particular line, and the auxiliary switch is operated either before or after the associated connector is operated in order to select ringing current of the proper character to signal the station desired. Thus it will be seen that there may be as many stations on a party line as there are different kinds of ringing current provided at the exchange, which usually does not exceed five. If it is desired to connect a greater number of stations on a party line, ten stations, for

example, the party line may be connected in mu tiple to two sets of bank contacts in the connector banks, and the ringers at the ten substations are connected half from each side of the line to ground. With this arrangement, and assuming that the lines are reversed between the two sets of bank contacts, half the stations on the line may be signalled by calling one set of bank conacts and the other half may be signalled by calling the other set of bank contacts. This arrangement is very satisfactory, so far as the operation thereof is concerned; but it is also nneconomical. since it reduces by one half the number of party'lines which may be handled by the group of connector switches. lhe ob ect of our invention, stated specificaly, is to providea selective signalling system of the general type described above whlch is adapted to signal twice the number of stations on a party line as there are different kinds of ringing current at the exchange, without, however, requiring that each party line be connected to two sets of bank contacts. We are thus able to double the number of party line stations which can be reached from a single group of connector switches.

There are other minor improvements wh ch to ether with the above will be described t ully hereinafter, reference being had to the accompanying drawin Referring to the drawing, which comprises a single sheet, we have shown therein sufficient of the apparatus in an automatic telephone system to enable our invention to be explained and understood. The reference character A indicates an automatic substation of the usual type, which has the usual talkin instrume'ntalities and the calling device for controlling the central office switches.

Substation A is connected with the central exchange b line conductors 11 and 12 which termiinate 1n the individual line or trunk selecting switch C. The line switch C is a switch of the well known rotary type whose wipers have no normal position and move in a forward direction only. As is well known the function of the individual line switch is to extend its associated line to an idle first selector switch when the receiver is raised at the substation to initiate a call. One of the first selector switches to which the line switch C has access in common with other similar line switches is indicated in the drawing by the rectangle D. Inasmuch as selector switches are well known in the art it has not been considered necessato show the circuits in detail. It may stated briefly that the seector D is a Strowger vertical and rotary switch of well known mechanical construction and operable according to the two wire system of control. When used in setting up a connection the selector responds to the first digit in the called number in order to select a desired group of connector switches, afterwhich the D has access to is connect with a trunk line extending to an idle connector in the selected fgroup. The above is of course true only a 1000 line system; if the capacity of the system is greater than this, second or third selectors will be interposed between the first selectors and connectors in the well ner. This is the usual percentage trunkin system, however, and need not be discuss in detail.

' Une of the trunk lines which the selector shown in the drawing as extending to the connector E, which is also a fitrowger vertical and rotary switch having a capacity of 100 subscribers lines. The

' connector E is operable according to the two till 943 the testcontact with which the test wiper holding circuit for the corner of the drawing and signalling any wire system of control like the selector D, and it responds to the last two digits in a called number to complete the connection to the called line.

One of the lines to which the "connector E as access is shown at the upper right hand comprises line conductors 101 and 102. This line is a party line, and substations AA inclusive, only one of which is shown completely, are connected in bridge of the line in the usual manner. The line switch C is asso ciated with the party line at the exchange and is similar to the line switch (3.

Just below the connector E we have shown an auniliar switch which is indicated b reference c aracter F. This is the switc referred to in the foregoing and when used in the present situation is generally called a frequency selecting switch. It comprises briefly, the wipers 122 and 123', and associated sets of bank contacts, the stepping magnet 120, and the release magnet 121. Th frequency selector F is individual to the con.- nector E. the two switches canoperate in selectively one of the ten stations on shown or another similar part lin is the rincipal subject matter of the invention an will now be described.

For this purpose it will be assumed that the subscriber at substation A desires to establish connection with the subscriber at substation A". When the receiver is re moved atthe callin station a circuit is completed over the con uctors 11 and 12 for the line relay 15. lUpo 15 the party line n energizing, rela closes a circuit at its armature 20 whic includes the winding of the switching relay 14 and the stepping magnet 16 in series; and at its armature 21 connects the test wiper 26 to the above circuit at a point midway between the said switching relay and the magnet. The operation now depends upon whether the trunk line with which the line switch'wipers are associated is bu or is not busy. lit the trunk line is busy t ere will be a ground potential upon understood man-f The circuit arrangement whereby is in engagement, the switching relay 14 will be sh rt clrcuited, and the stepping ma net 16, which interrupts its own circuit, wi 1 be operated in the manner of a buzzer to advance the switch wipers in search of an idle trunk line; However, we may assume in the present case that when the (all is initiated the trunk line upon which the wipers of the line switch are standing is idle. Under these circumstances when the line relay 15 is energized the switching relay 1t will not be short circuited and the stepping magnet 16 will not be operated because of the high resistance of the said switching relay. The latter relay, however, is energized, grounds the test wiper 26 at its armature 18, and at its armatures 17 and 19 disconnects the line conductors l1 and 12 from the windings of the line relay 15 and from ground, respectively, and extends them by way of wipers and 27 and bank contacts 28 and 30 to the line relay (not shown) of the first selector D. The line and release relays of the selector D are now ener ized in the usual manner and the latter re ay grounds the release trunk conductor of the trunk line in order to establish a holdin circuit for the switching relay 14 of the me switch 0. This operation is well understood and need not be explained further.

The callin subscriber may now operate his calling evice in-accordance with the first digit in the desired number. Tn re sponse to the interruptions in the line thus godueed the vertical magnet of the selector is operated under control of the line relay to raise the wipers -42, inclusive, to the particular level in which are terminated the trunk lines extending to the desired group of connector switches. Thereafter the rotary or trunk selecting movement is initiated automatically in the usual manner and the .wipers are rotated in search of an idle trunk line. Assuming that the trunk line shown in the drawing is the first idle trunk line when the wipers arrive at bank contacts tit-45, inclusive, the test wiper 41 will find no ground potential upon the test contact 4% and the rotation of the switch will cease. When this occurs the incoming line conductors are extended in the usual manner b way of the switch-wipers 10 and 42, ban contacts 43 and 45, and contact springs controlled by the reversing relay to the windings of the double wound line relay 51 of the connector E.

When the line is extended as above described the line relay 51 is energized over the line circuit to close a circuit for the slow acting release relay 52. Upon energizing, relay 52 prepares a circuit for the vertical magnet 58 at its armature .65, and at gits armature 06 connects ground to the release trunk conductor 17, thereby completing? a selector D and the till Mid

llll

lld

ldd

of the desired number,

line switch C in the well known manner. The calling subscriber may now operate his calling device in accordance with the next digit in the desired number. As a result the line relay 51 is deenergized a plurality of times,

and at the first deenergization transmits a current impulse to the vertical magnet 58 over the following circuit: from ground at G, by way of armature 64 and its resting contact armature and its working contact, oti 63, winding of the slow acting series relay 53, and the winding of the vertical magnet 58 to battery. By the operation of the vertical magnet the wipers 90-92, inclusive, are raised step by step until they stand opposite the level in which is terminated the line of substation A. I The slow acting series relay 53 is energized in series with the vertical ma at and by means of its armature 67 maintains the circuit of the vertical magnet intact after the off normals rings-have been shifted, which occurs on t e first. vertical step. At the end of the vertical movement of the switch, relay 53 is deenergized and transfers the operating circuit to the rotary magnet 59.

The subscriber'will now operate his calling device in accordance with the next digit which has to do with the line selection. When the calling device is operated the line relay 51 responds as before and sends impulses to the rotary magnet 59 over the following circuit: ground at G, armature 64 and its resting contact, armature 65 and its working contact, oif .normal springs 61 and 62, armature 67- and its resting contact, resting contact of armature 72 and the said armature, winding of the slow acting series relay 56, armature 81 and its resting contact, and the winding of the rotary m et 59 to battery. By the operation of t e rotary magnet the wipers 90-92, inclusive, are rotated step by step and are finally brought to rest in engagement with the bank contacts in which the line of substation A" is terminated, these bank contacts being indidated in the drawing by reference characters 93, 94, and 95. The slow acting relay 56 is energized in series with the rotary magnet and retains itsarmature attracted throughout the rotary movement of the switch. At its armature 74, relay 56 connects the test wiper 91 with the test relay 55, and at its armature the said relay 56 closes a shunt around the contact at armature 72 of the test relay. The latter operation is to prevent the test relay from opening the rotary magnet circuit while the test wiper. is passing over busy test contacts.

It. will be assumed. first, that the called line is busy. Such being the case, when the test wiper 91arrives at test contact 94 it will find a ground potential thereon, the

normal springs 61 and which is the last digit final digit in the number,

rotary magnet circuit. at its armature 72, and at its armature 73 connects a lead from the busy signalling'machine'to the lower heavy talking conductor. By this operation an audible signal is transmitted to the calling subscriber and being advised thereby that the called line is inaccessible for the time being he will ban up his receiver.

Having explained t e operations which take place when the called line is busy it will now be assumed that the line is idle when called. Under these. circumstances when the test wiper 91 arrives attest contact 94 it will find no ground tential and the test relay 55 will not i energized. Then when the slow acting relay 56-deenergizes at the end of the rotary movement of the switch a circuit is completed for the switching relay 57 as follows: from the grounded release trunk conductor 47 by way of armature 71 and its re'sting contact, upper winding of the switching relay 57, resting contact of armature 74 and the said armature, test wiper 91, test contact 94, winding of the switching relay 14', and the winding of the stepping magnet 16 to battery; Relays 57 and 14' are ener ized in series over the above circuit, and t e latter relay is operated to clear the called line of its normal battery and ground connections in theline switch C. It is noted that the relay 14' is not fully operated at this time, due to a mechanical interlocking arrangement between the armature of its relay and the armature of the line relay 15', and the wipers of the line switch C are not connected up. In the. connector E, when the switching relay 57 is energized it'establishes a logking circuit for itself at its armature 80, opens the circuit of the test relay 55 at its armature 79, grounds thertest wiper 91 at its armature 78, transfers the operating circuit to the stepping magnet 120 of the frequency selecting switch F at its armature 81, closes a circuit at its armature 82 which provides for transmitting a tone'signal to the calling subscriber during the ringing operation, completes the connection 90 and 92.

The calling subscriber may now 0 crate his calling device in accordance wit to the line wipers which is the digit which selects the pro er frequency of ringing current for signalling the partlcular station wanted. The substations A A inclusive, have been numbered for convenience in accordance with the digits to which they correspond, and since the substation A is the wanted substation in the present case and at its armatures 77 and 83 the ' rest in engagement the final digitto be called erated for this digit the line relay 51 transmits ten impulses of current to the stepping magnet 1200f the frequency selector F over the following circuit: from ground at G by way of armature 64 and its resting contact, armature 65 and its working contact,-ofl normal springs 61 and 62, armature 87 and its resting contact, resting contact of armature 72 and the said armature, winding of slow acting series relay 56, armature 81 and its working contact, armature 87 and its resting contact, and the windin of the stepping magnet 120 to battery. y the operation of magnet 120 wipers 122 and 123 are iven a step by step movement and are fina ly brought to with the tenth contacts in their respective banks. The slow acting relay 56 is energized in series with the magnet 120 but without ellect so far as the connector E is concerned. At the end of the series of impulses transmitted to the magnet 120. relay 56 com leted for relay 89 as follows: ground at wiper 122,. tenth contact in the bank associated with said wiper, conductor 135,

. winding of the reversing relay 96, armature 7 above circuit relays 96-and 89 are interrupter,

the bank associated with wiper 123, wiper.

76 and its resting contact, and the winding of relay 89 to battery. By the closure of the energized in series and the former relay, by1 means of ai-matures 84: and 85, reverses t e connections to the line wipers 90 and 92 in an ob.- vious manner. Relay 89, upon energizing, breaks the circuit of the stepping magnet 120 at armature 87, prepares a circuit for the release magnet 121 at armature 86, and at armature 88 completes the signalling circuit as follows: from the grounded generator Gen, through the contact of the ringing conductor 130, tenth contact in 123, conductor 137, armature 88 and its working contact, resting contact of armature 70 and the said armature, tact of armature 83 and the said armature, working contactof armature 84.- and the said armature, wiper 90, bank contact 93, conductor 101, the normally closed switch hookcontact at substation A, and the ringer at the saidsubstation to ground. The above circuit is intermittently opened and closed by the operation oicthe ringing interrupter and the ringer at substation A is thus operated at intervals to signal the called subscriber. It is understoo of course, that the ringing current also flows through the ringers at substations A A", inclusive to ground at the same time, but the ringers at theseother substations are tuned so that they will not respond to the frequency of ringing current which is now in use. his is according to the well known practice of harmonic signalling, and it follows that the is deenei'gized and a circuit is working con I lessees ri n at substation A is the only one which is operated; When the called sub-- scriber at substation A removes his receiver to answer the call the ringer thereat is disconnected and the ringing completed over a metallic the other line conductor 102 and the upper winding of the ring out ofi relay 5% at the connector E. The ring out all relay 54: is now energized and establishes a locking circuit for itself at its armature 69, opens the rin ing circuit at its armatures 68 and 70), an at the working contacts of these same armatures finally completes the talking circuit.

I The required connection has now been established and the calling and called subscribers may converse as desired. Current for the transmitter at substation A. is six plied-through the windings of the doub e wound line relay 51 While current for the transmitter at substation- A is supplied through the windings of the back bridge or reversing relay 50. course energized and reverses the direction of current flow in the calling line during conversation. Although this operation is circuit is' circuit including The latter relay is of.

of no utility in connection with the appara-- tus shown it is a standard operation for use in controllin measured service equipment and is there ore included. When the conversation is finislied both subscribers will hang up their receivers. When the receiver is replaced at substation A the line and release relays 51 and 52 are deener ized and the latter relay closes a circuit fort erelease magnet 60, which operates to restore the connector E to normal position in the usual manner. Relay 52 also disconnects ground from the release trunk conductor 47, there- .by. breaking the holding circuits of the selector D and line switch C and these two switches are accordingly restored to normal also. At the same time that relay 52 closes the circuit ofrelease magnet 60 said relay closes a circuit by way of armature 86 of relay m 121 of the frequency selecting switch F. By the operation of the release magnet 121 the holding and driving pawls are withdrawn from the ratchet 89 which includes the releasemagnet of switch F and the wipers are restored to normal position. Thus all Y the apparatus in use has been bleed and made ready for use in another connection A brief explanation will now be given of the manner in which the other stations on .the line are signalled. Substations A", A",

A and A, may be reached by calling digits 6, 7, 8, and 9, respectively, as the final digits, and the operations are exactly the same as when substation A is called except that a difi'erent frequency of ringing current is selected. lit will be understood in this connection that conductors 13( )-234, inclusive, all extend to separate ring ng current generators, and these enerators are all of different frequency. Alt ough only one of these ground. In order to operate the rin ers at the remaining stations, substations 1 U, inclusive, which are connected from the hne conductor 102 to ground, digits 1," 2, 3, 4,

Y and 5, respectively, must be called as the final digits. Sup ose, for example, that it is desired to call t esubstation A", the ringer at which station is tuned to the same frequency as the rin er at substation A but which is connecte 102 to ground. The final di it to be called in this case is the digit 5 an the wipers of of the frequency selecting switch a circuit is" closed for the relay 89 the same as before, except that in the present case the circuit is established over conductor 136 and does not include the reversing relay 96. By the movement of wiper 123 the ringing generator five contacts in the shown in the drawingJ is selected, the first wiper 123 being connected in multiple with the last five, and when relay 89 energizes a ringing circuit is completed substantially the same as previously described except that in the present case the ringing current is applied to the line by way of wiper 92 instead of wiper 90, and hence flows over the line conductor 102 and through the-ringers at substations A A, inclusive, to ground.

he ringer at substation A is accordingly operated. Substations A to A, inclusive, may be called in the same manner by using the final digits which correspond to these substations.

It will be seen that by providing a reversing rela in each connector switch we are able to ouble the number of stations on the line without having to use two sets of contacts for such line in the connector banks. The reversing relay performs the same function as the reversal in the line conductors between the two sets of bank contacts and the re uired result is thus accomplished in a simp er and more ecomonical manner.

Having described our invention. what we consider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims.

'at we claim as our invention is:

1. In a selective ringing telephone system, party lines, a connector switch provided with fre uency selecting means, there being only ha f as many different frequencies of ringing current to be selected as there from the line conductor line,

ank associated with are stations on a party line, and means in saidconnector cooperating with said frequency selecting means whereby all the statrons on a arty line may be selectively signalled, said selecting mechanism and a separate line conductor reversing device.

2. In a telephone system, substation ringers connected from opposite sides of said hne to ground, an automatic switch for extending a connection to said line, said switch including a pair-of line Wipers, a plurality of sources of ringing current of different character there being half 'as many of said sources as there are stations on said line, means associated with said switch for selecting one of said sources, and means separate from the last named means for connecting the selected, source to either of said wipe-rs.

3.- In a telephone system, different sources of ringing current at the exchange, a party substation ringers equal in number to the number of said sources connected from one side of said line to ground, a like number of ringers connected from the other side of said line to ground, means including an automatic connector switch for extending a connection to said line, means associated with said connector for selectin any one of said sources, and means operab e thereafter for controlling the connectin of the selected source to either side 0 said line to signal any desired station thereon.

4. In a telephone system, different sources of ringing current at the exchange, a party line, substation ringers equal in number to a party line,

'the number of said sources connected from sources and for connecting the selected source to either side of the connected line to signal any desired station thereon.

5. In a-telephone system, a party line, a plurality of stations and ringers thereat connected from opposite sides of said line to ground, a plurality of different ringing current sources at the exchange equal in number to half the number of said stations, an automatic connector switch at which said line terminates in a single set of bank contacts, means for operating said connector to connect with said contacts,'a fr uency selector for then selecting any one 0 said currentsources, and a second selecting d'evice actuated. after said frequency selector has operated for connecting the selected source to either side of said line to sign-a1 any desired one of said stations.

' connected from opposite sides of said line I relay device, said line by way to ground, a plurality of difierent freqiliency ringing current sources at the exc ange equal in number to half the number of said stations, an automatic connector switch at which said line. terminates in a vsingle set of bank contacts, means for operating said connector to connect with said contacts, and means for then selecting any one of said current sources and connecting the same to either side of said line to signal any desired one of said stations, said means comprising, a reversing relay in said connector and a frequency selecting switch including means for controlling said relay.

7. In a telephone system, a partly line. a plurality of stations and ringers thereat connected from opposite sides of said line to ground, a plurality of different frequency ringin current sources at the exchange equal in number to half the number of saidstations, an automatic connector switch at which said line terminates in a single set of bank contacts, means for operating said connector to connect with said cont-acts, a frequency selecting switch associated with said connector for selcting any one of said current sources, and a relay in said connector controlled by said frequency selecting switchvfor connecting the selected source to. either side of said line to signal any desired one of said stations.

8. In a telephone system, a partlyline, a plurality of stations and ringers thereat connected from opposite sides of said line to ground, a plurality of different freuency ringing current sources at the ex- 0 'iange equal in number to half the number of said stations, an automatic connector switch at which single set of bank contacts, means for opera-ting said connector to connect withsaid contacts, a fire ue'ncy selecting switch associated with sai connector for selecting any one of said current sources, and a reversing in said connector for connecting the selected current source to either side of said line to signal any desired one of said stations.

9. In a telephone system, a connector switch, a line accessible thereto, a plurality of sources of ringing current, a selecting means for extending a connection to of said connector switch, means for operating said selecting device said line terminates in'a aeeaeoe to select any one of said sources oflcurrent, a relay, a second relay, a circuit for the first relay including mid second relay, a second circuit for said first relay exclusive of said second relay, and means controlled by said selecting device for closing one or the other of said circuits rent from the selected/sources to one side or the other of the called line.

so as to apply ringing'cur- I 10. In a telephone system, a connector switch, aline accessible thereto, a plurality of sources of ringing current, a selecting I device, 'means for extending a connection to said line by way of saidconnector switch,

means for operating said selecting device to select any one of said sources of current, a relay, a second relay, means for applying. ringin current from the selected source to one si e of the called line by energizin the first relay alone, and means for app ying current to the called ine by energizing-both of said relays together.

11. In a telephone system, a connector switch, a line accessible thereto, a plurality of sources of ringing current, a selecting device, means for extending a connection to said line by way of said connector switch, means for operating said selecting device to select any one of said sourcesof current, a relay, a second relay, meansfor applying ringi current from the selected source to one si e of the called line by energizing the first relay-alone, and means for applying ringing current to the otherv side of the called ine by energizing both of s id relays together, both of said applying cans being controlled by the position of said selectin device.

1%. n a telephone system, a connector switch, a line accessible thereto, a plurality of sources of ringing current, a selecting device, means for extending a connection to said line by way of said connector switch,

means for operating said selecting device a second relay, means for applying other side of the I 

